Ingestion of pathogens, especially bacterial pathogens, but including viruses and other disease causing microorganisms, is a common problem in most animals. Pathogens have been known to cause illnesses in animals that have wide ranging deleterious effects including weight loss, diarrhea, abdominal cramping, and renal failure. For animals that are immunosuppressed or malnourished, even just the effects of diarrhea can be fatal. Pathogens are often transferred between animals where poor hygiene conditions exist, and sometimes communicability cannot be prevented even when great care is taken. The most common solution to this problem has been to provide antibiotics to the animals; however, this solution is not only costly, but it also can result in the generation of antibiotic-resistant strains of bacteria.
Extreme health risks result when humans consume pathogens in contaminated food products such as sprouts, lettuce, meat products, unpasteurized milk and juice, and sewage-contaminated water, for example. The problem is particularly prevalent in the beef and dairy industry. Pathogens present on a cow's udder or on milking equipment may find their way into raw milk. Meat can become contaminated during slaughter, and pathogenic organisms can be mixed into large quantities of meat when it is ground. When humans eat meat, especially ground beef, that has not been cooked sufficiently to kill any pathogens present in the beef, serious and life-threatening infections can result. This is a difficult problem to solve because contaminated meat often looks and smells perfectly normal. Furthermore, the number of pathogenic organisms needed to cause disease is extremely small, thus making detection extraordinarily difficult.
Pathogens that cause disease in the intestinal tract are known as enteropathogens. Examples of enteropathogenic bacteria, or enterobacteria, include Staphylococcus aureus, particular strains of Escherichia coli (E. coli), and Salmonella spp. Whereas most of the hundreds of strains of E. coli are harmless and live in the intestines of animals, including humans, some strains, such as E. coli O157:H7, O111:H8, and O104:H21, produce large quantities of powerful shiga-like toxins that are closely related to or identical to the toxin produced by Shigella dysenteriae. These toxins can cause severe distress in the small intestine, often resulting in damage to the intestinal lining and resulting in extreme cases of diarrhea. E. coli O157:H7 can also cause acute hemorrhagic colitis, characterized by severe abdominal cramping and abdominal bleeding. In children, this can progress into the rare but fatal disorder called hemolytic uremic syndrome (“HUS”), characterized by renal failure and hemolytic anemia. In adults, it can progress into an ailment termed thrombotic thrombocytopenic purpura (“TTP”), which includes HUS plus fever and neurological symptoms and can have a mortality rate as high as fifty percent in the elderly.
Reduction of risk for illnesses due to food borne pathogens can be achieved by controlling points of potential contamination. The beef industry has recognized the need to investigate pre-harvest control of pathogens, particularly E. coli O157:H7, due to potential runoff contamination, contact with humans, and the transfer of pathogens during meat processing. In particular, undercooked or raw hamburger (ground beef) has been implicated in many documented outbreaks as containing E. coli O157:H7.
Accordingly, there is a recognized need for compositions and methods for reducing or eliminating the growth of enteropathogens such as E. coli O157:H7 for the health benefits to the animals. Furthermore, there is an important need for reducing or eliminating the growth of enteropathogens in meat and milk producing animals prior to their harvest for the benefit of consumers. By such reduction or elimination in food animals, consumers of beef, dairy, and other food products will be better protected from the risk of consuming such pathogens.